Basic FFT

1, Sine wave

2, Larger number of cycles

The more cycles of a signal, the higher the certainty of the frequency. This is why we observe a linewidth of 17 Hz for the 10-cycle signal, and a linewidth of 1.7 for the 100-cycle signal.

The nyquist frequency is defined by the sample rate, which is the same for both signals. However, the number of frequency bins is defined by the number of total samples. Therefore, the range of frequency of the two signals is the same, but the one with more samples is slightly closer to the nyquist frequency due to the higher resolution.

Sine and Square Waves

Tuning Forks

Whistle

Human Voice

Musical Harmonics

Optional

y = sin(2pi100x) from x = 0 to 0.1 seconds, using 100 points and only 10 points